Attornment, subordination and non-disturbance clauses are all provisions that determine priority to the premises as between lenders, mortgagees, purchasers of the building, and existing tenants. Attornment is an assurance that the lease terms will be fulfilled by the new landlord and that the lease will apply to them in full (attorned by the transferree, or they "step into the shoes" of the old landlord). Subordination language in the agreement will be inserted in the case of a lender financing the building by way of a mortgage. The subordination clause will be requested by the lender to be inserted into the lease by the landlord to give priority to any future or existing mortgages over the existing lease. Without the subordination clause, the priority will be determined by the timing of the lease and the mortgage, i.e. whichever comes first will have priority. The subordination clause operates to ensure the mortgage will have priority. A clause that may be negotiated is a "non disturbance provision" which states that in the case of a sale, the new owner will not disturb the underlying lease.